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RevLimit 11-05-2012 10:12 PM

Shuttering/Bucking, Power Loss Between 3,500 to 5,000 RPM
I'm having power loss issues between 3,500 to 5,000 RPM. Usually once the RPMs reach 5,000 the car will eventually begin to pull. This only happens when the car is in gear and it's very irritating to have bucking and jerking when I mash the gas until 5,000 RPM when a get a moment of nice power.

I have noticed that in the cold mornings the car RPMs will sometimes jump to 2,000 RPM until the engine gets warm.

It also sounds like sometimes the engine beings to backfire.

So far I have tried the following.

Replaced the fuel filter.
Replaced the spark plugs, gapped correctly.
Replaced spark plug cables.
Replaced the manifold cup-links with the CFM ones.
Replaced fuel pressure regulator vacuum line.

Which is the most likely cause

Air leak behind the MAF sensor?
Failing head-gasket?
Fuel not enough fuel pressure? Although the engine runs strong above 5,000 RPM.

Thanks in advance.

Jaketet 11-05-2012 10:30 PM

tried cleaning the MAF?

RevLimit 11-06-2012 08:03 AM


Originally Posted by Jaketet (Post 4442048)
tried cleaning the MAF?

I did not think that the MAF could be cleaned? How can I clean the MAF sensor without damaging it?

1turbofocus 11-06-2012 08:42 AM

The best advice I can give is find a local member with a xcal and do a datalog , I will be glad to look it over and help with the problem

Changing parts till you find the issue gets very costly as I am sure your finding out


Scout706 11-06-2012 08:43 AM

Very carefully. Seriously, it's usually a thin platinum wire. If you're unsure, maybe a mechanic is the best way to go.

Jaketet 11-06-2012 09:17 AM

They have MAF cleaner that you spray onto the wire. Also, datalogging like Tom said will give you a better idea of where to start.

RevLimit 11-06-2012 10:47 AM

I will buy some of the MAF cleaner and give that a try. Do any of you know someone in the Atlanta area that has a dataloger?

Thanks for the feedback everyone!

SVTb4U 11-08-2012 04:44 PM

I'm in Lilburn/Lawrenceville area
I'd be glad to help with my Xcal.

RevLimit 05-15-2014 06:38 PM

The problems I was experiencing above were caused by a faulty ignition coil pack. I purchased a replacement Ford OEM pack and the car runs great now.

Sorry for not updating everyone sooner.

sailor 05-15-2014 07:35 PM

Tx for posting your cure!

(and nice to see you posting here again)

Had a question just today from a member with the same symptoms, this may help them.

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